Materials engineers often create new alloys in an effort to improve the properties of an existing material. ZnO based semiconductors show promise in applications like light-emitting diodes, but their performance can be enhanced by the addition of small amounts of cadmium.

One material that has been studied can be represented by the formula Zn_0.843Cd_0.157O. (These materials are solid solutions, and so they can have variable compositions. The noninteger coefficients do not imply fractional atoms.) Express the composition of this alloy in terms of

(a) At%, 

(b) Mol%, and 

(c) Wt%